Methods and apparatus for imaging with detectors having moving detector heads

ABSTRACT

Methods and apparatus for imaging with detectors having moving heads are provided. One apparatus includes a gantry and a plurality of detector units mounted to the gantry. At least some of the plurality of detector units are movable relative to the gantry to position one or more of the detector units with respect to a subject. The detector units are movable along parallel axes with respect to each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of, and claims priority to and thebenefit of the filing date of U.S. application Ser. No. 15/612,226,filed Jun. 2, 2017, which is a Continuation of, and claims priority toand the benefit of the filing date of U.S. application Ser. No.14/016,943, filed Sep. 3, 2013, (now U.S. Pat. No. 9,662,079) and U.S.application Ser. No. 15/082,929, filed Mar. 28, 2016, the subject matterof which are herein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates generally to apparatus andmethods for diagnostic medical imaging, such as Nuclear Medicine (NM)imaging.

In NM imaging, systems with multiple detectors or detector heads may beused to image a subject, such as to scan a region of interest. Forexample, the detectors may be positioned adjacent the subject to acquireNM data.

In NM imaging systems, the resolution of the detector, in particular thegamma detector, is determined by the resolution of the detector (basedon the size of pixels of the detector) and the resolution of acollimator attached to the detector. The resolution degrades withdistance of the detector, specifically the collimator, from the subject.

In Single Photon Emission Computed Tomography (SPECT) systems havingmoving detector heads, the detectors may be positioned to focus on aregion of interest. For example, a number of pinhole gamma cameras maybe positioned to view a small region of interest (e.g., heart of thesubject). However, these moving detector heads are not configured tooperate, for example, move in such a manner to allow general purposeimaging, such as of the entire subject. For example, because of the sizeand spacing of the detector heads, when imaging a smaller subject, thedetector heads may collide when moved in close proximity to the subject,thereby preventing placement of the detector heads close to the subject.Moreover, for larger subjects, gaps may exist between the detectorsbecause the detectors have to be moved apart to allow for focusing onthe field of view. Accordingly, because the detector heads cannot bemoved in close proximity to the subject or as a result of the gapsbetween the detector heads, image resolution is reduced.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, an imaging system is provided that includes a gantryand a plurality of detector units mounted to the gantry. At least someof the plurality of detector units are movable relative to the gantry toposition one or more of the detector units with respect to a subject.The detector units are movable along parallel axes with respect to eachother.

In another embodiment, a Nuclear Medicine (NM) imaging system isprovided that includes a gantry and a pair of opposing support memberscoupled to the gantry, wherein the support members are on opposite sidesof the gantry and in parallel alignment with each other. The NM imagingsystem further includes a plurality of movable detector carriers coupledto each of the support members, with each of the plurality of movabledetector carriers having a proximate end coupled to a respective supportmember and a distal end. The plurality of movable detector carriersextend from the respective support member and are aligned in parallelwith each other along the support member. The NM imaging system alsoincludes at least one detector unit coupled to each of the distal endsof the plurality of movable detector carriers, wherein the detectorunits are rotatable about the distal end of the movable detectorcarrier. The movable detector members are configured to move thedetector unit coupled thereto away from and towards the gantry.

In another embodiment, a method of imaging is provided that includescontrolling movement of one or more support members coupled to a gantryto position one or more detector arrays relative to a patient table. Themeth further includes controlling movement of one or more detector unitsof the detector array to further position the one or more detector unitsrelative to the patient table, wherein the one or more detector unitsare coupled to a plurality of movable detector carriers having parallelaxis of movement with respect to each other. The method also includesacquiring image data using the one or more detector units, whereinacquiring the image data comprises rotating the one or more detectorunits relative to the movable detector carriers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a Nuclear Medicine (NM) imagingsystem in accordance with an embodiment.

FIG. 2 is a schematic block diagram illustrating movement of detectorunits in accordance with an embodiment.

FIG. 3 is a schematic block diagram illustrating detector unitpositioning for different sizes of subjects in accordance with anembodiment.

FIG. 4 is a schematic block diagram illustrating detector unitpositioning for different sizes of subjects in accordance with anotherembodiment.

FIG. 5 is a schematic block diagram illustrating detector unitpositioning for breasts of a subject in accordance with an embodiment.

FIG. 6 is a schematic block diagram illustrating detector unitpositioning for a head of a subject in accordance with an embodiment.

FIG. 7 is a schematic block diagram illustrating movement of detectorunits in accordance with another embodiment.

FIG. 8 is a schematic block diagram illustrating additional detectorunit supports in accordance with an embodiment in one position.

FIG. 9 is a schematic block diagram illustrating the additional detectorunit supports of FIG. 8 in another position.

FIG. 10 is a schematic block diagram illustrating movement of detectorunits in accordance with another embodiment in one position.

FIG. 11 is a schematic block diagram illustrating movement of detectorunits of FIG. 10 in another position.

FIG. 12 is a schematic block diagram illustrating a configuration ofdetector units in accordance with an embodiment.

FIG. 13 is a schematic block diagram illustrating a configuration ofdetector units in accordance with another embodiment.

FIG. 14 is a schematic block diagram illustrating different rotationalmovement ranges for different detector units in accordance with anembodiment.

FIG. 15 is a schematic block diagram illustrating a configuration ofdetector units in accordance with another embodiment.

FIG. 16 is a schematic block diagram illustrating movement of a detectorunit within a housing in accordance with an embodiment.

FIG. 17 is a flowchart of a method for controlling movement of detectorunits in accordance with various embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description ofcertain embodiments, will be better understood when read in conjunctionwith the appended drawings. To the extent that the figures illustratediagrams of the functional blocks of various embodiments, the functionalblocks are not necessarily indicative of the division between hardwarecircuitry. For example, one or more of the functional blocks (e.g.,processors or memories) may be implemented in a single piece of hardware(e.g., a general purpose signal processor or a block of random accessmemory, hard disk, or the like) or multiple pieces of hardware.Similarly, the programs may be stand alone programs, may be incorporatedas subroutines in an operating system, may be functions in an installedsoftware package, and the like. It should be understood that the variousembodiments are not limited to the arrangements and instrumentalityshown in the drawings.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of are not intended to beinterpreted as excluding the existence of additional embodiments thatalso incorporate the recited features. Moreover, unless explicitlystated to the contrary, embodiments “comprising” or “having” an elementor a plurality of elements having a particular property may includeadditional elements not having that property.

Various embodiments provide apparatus and methods for controlling themovement of a plurality of imaging detectors to position the imagingdetectors adjacent subjects, such as patients of different sizes. Forexample, in various embodiments a general purpose Nuclear Medicine (NM)camera with an array of heads that are individually and independentlymovable is provided. In some embodiments, one or more of the heads arecapable of a plurality of types of movement, such as rotation andparallel linear motion. For example, the detector heads may beconfigured to move downwards and/or towards a subject in parallel planesor along parallel axes (e.g., comb like movement) instead of radialmotion toward the center of a gantry. By practicing various embodiments,efficient placement of detector heads around subjects of different sizesand shapes is provided, such that resolution and sensitivity areincreased or maximized.

FIG. 1 is a schematic illustration of a Nuclear Medicine (NM) imagingsystem 100 having a plurality of imaging detectors mounted on a gantry.In particular, a plurality of imaging detectors 102 are mounted to agantry 104. In the illustrated embodiment, the imaging detectors 102 areconfigured as two separate detector arrays 106 and 108 coupled to thegantry 104 above and below a subject 110 (e.g., a patient), as viewed inFIG. 1. The detector arrays 106 and 108 may be coupled directly to thegantry 104, or may be coupled via support members 112 to the gantry 104to allow movement of the entire arrays 106 and/or 108 relative to thegantry 104 (e.g., translating movement in the left or right direction asviewed in FIG. 1). Additionally, each of the imaging detectors 102includes a detector unit 114 mounted to a movable detector carrier 116(e.g., a support arm or actuator that may be driven by a motor to causemovement thereof) that extends from the gantry 104. In some embodiments,the detector carriers 116 allow movement of the detector units 114towards and away from the subject 110, such as linearly and in parallelto each other. Thus, in the illustrated embodiment the detector arrays106 and 108 are mounted in parallel above and below the subject 110 andallow linear movement of the detector units 114 in a single direction(indicated by the arrow L), illustrated as perpendicular to the supportmember 112 (that are coupled generally horizontally on the gantry 104).However, other configurations and orientations are possible as describedherein.

Each of the imaging detectors 102 in various embodiments are smallerthan a conventional whole body or general purpose imaging detector. Aconventional imaging detector may be large enough to image most or allof a width of a patient's body at one time and may have a diameter ofapproximately 40 cm. In contrast, each of the imaging detectors 102 mayinclude one or more detector units 114 coupled to a respective detectorcarrier 116 and having dimensions of 4 cm to 20 cm and may be formed ofCadmium Zinc Telluride (CZT) tiles or modules. For example, each of thedetector units 114 may be 8×8 cm in size and be composed of a pluralityof CZT pixelated modules (not shown). For example, each module may be4×4 cm in size and have 16×16=256 pixels. In some embodiments, eachdetector unit 114 includes a plurality of modules, such as an array of1×7 modules. However, different configurations and array sizes arecontemplated including, for example, detector units 114 having multiplerows of modules.

It should be understood that the imaging detectors 102 may be differentsizes and/or shapes with respect to each other, such as square,rectangular, circular or other shape. An actual field of view (FOV) ofeach of the imaging detectors 102 may be directly proportional to thesize and shape of the respective imaging detector.

The gantry 110 may be formed with an aperture 118 (e.g., opening orbore) therethrough as illustrated. A patient table 120 is configuredwith a support mechanism (not shown) to support and carry the subject110 in one or more of a plurality of viewing positions within theaperture 118 and relative to the imaging detectors 102. Alternatively,the gantry 104 may comprise a plurality of gantry segments (not shown),each of which may independently move a support member 112 or one or moreof the imaging detectors 102.

The gantry 104 may also be configured in other shapes, such as a “C”,“H” and “L”, for example, and may be rotatable about the subject 110.For example, the gantry 104 may be formed as a closed ring or circle, oras an open arc or arch which allows the subject 110 to be easilyaccessed while imaging and facilitates loading and unloading of thesubject 110, as well as reducing claustrophobia in some subjects 110.

Additional imaging detectors (not shown) may be positioned to form rowsof detector arrays or an arc or ring around the subject 110. Bypositioning multiple imaging detectors 102 at multiple positions withrespect to the subject 110, such as along an imaging axis (e.g., head totoe direction of the subject 110) image data specific for a larger FOVmay be acquired more quickly.

Each of the imaging detectors 102 has a radiation detection face, whichis directed towards the subject 110 or a region of interest within thesubject. The radiation detection faces are each covered by or havecoupled thereto a collimator 122. The actual FOV for each of the imagingdetectors 102 may be increased, decreased, or relatively unchanged bythe type of collimator 122. In one embodiment, the collimator 122 is amulti-bore collimator, such as a parallel hole collimator. However,other types of collimators, such as converging or diverging collimatorsmay optionally or alternatively be used. Other examples for thecollimator 122 include pinhole, parallel-beam converging, divergingfan-beam, converging or diverging cone-beam, multi-bore converging,multi-bore converging fan-beam, multi-bore converging cone-beam,multi-bore diverging, or other types of collimator. In some embodiments,at least two types of collimators are used.

Optionally, multi-bore collimators may be constructed to be registeredwith pixels of the detector units 114, which in one embodiment are CZTdetectors. However, other materials may be used. Registered collimationmay increase spatial resolution by forcing photons going through onebore to be collected primarily by one pixel. Additionally, registeredcollimation may increase sensitivity and energy response of pixelateddetectors as detector area near the edges of a pixel or inbetween twoadjacent pixels may have reduced sensitivity or decreased energyresolution or other performance degradation. Having collimator septadirectly above the edges of pixels reduces the chance of a photonimpinging at these degraded-performance locations, without decreasingthe overall probability of a photon passing through the collimator.

A controller unit 130 may control the movement and positioning of thepatient table 110, imaging detectors 102, gantry 104 and/or thecollimators 122. A range of motion before or during an acquisition, orbetween different image acquisitions, is set to maintain the actual FOVof each of the imaging detectors 102 directed, for example, towards or“aimed at” a particular area or region of the subject 110 or along theentire subject 110.

The controller unit 130 may have a gantry motor controller 132, tablecontroller 134, detector controller 136, pivot controller 138, andcollimator controller 140. The controllers 130, 132, 134, 136, 138, 140may be automatically commanded by a processing unit 150, manuallycontrolled by an operator, or a combination thereof. The gantry motorcontroller 132 may move the imaging detectors 102 with respect to thesubject 110, for example, individually, in segments or subsets, orsimultaneously in a fixed relationship to one another. For example, insome embodiments, the gantry controller 132 may cause the imagingdetectors 102 and/or support members 112 to rotate about the subject110, which may include motion of less than or up to 180 degrees (ormore).

The table controller 134 may move the patient table 120 to position thesubject 110 relative to the imaging detectors 102. The patient table 120may be moved in up-down directions, in-out directions, and right-leftdirections, for example. The detector controller 136 may controlmovement of each of the imaging detectors 102 to move closer to andfarther from a surface of the subject 110, such as by controllingtranslating movement of the detector carriers 116 linearly towards oraway from the subject 110 (e.g., sliding or telescoping movement).Optionally, the detector controller 136 may control movement of thedetector carriers 116 to allow coordinated move of the detector array106 or 108. For example, the detector controller 136 may control lateralmovement of the detector carriers 116 illustrated by the L arrow (andshown as left and right as viewed in FIG. 1). In some embodiments,proximity sensors may be used to guide the controllers to bring thedetectors 102 in proximity to (e.g., within close range, such as 1-5 cm)from the subject 110 without colliding with or contacting the subject110. Alternatively or additionally, the shape of the subject 110 (e.g.,patient shape) may be known from imaging the subject 110 with anothermodality such as CT or 3D optical imaging and the information regardingthe shape of the subject 110 used to position the detectors 102.Optionally, in some embodiments, at least some of the detectors 102include a Pressure Sensing Device (PSD) capable of detecting physicalcontact of a sensor with the subject 110 or other solid objects andprevent or halt motion of at least one of the detectors 102, patient bed120, or gantry 104 that may, for example, cause harm to the subject 110.

The pivot controller 138 may control pivoting movement of the detectorunits 114 at ends of the detector carriers 116 and/or pivoting movementof the detector carrier 116. For example, one or more of the detectorunits 114 or detector carriers 116 may be rotated about at least oneaxis to view the subject 110 from a plurality of angular orientations.The collimator controller 140 may adjust a position of an adjustablecollimator, such as a collimator with adjustable strips (or vanes) oradjustable pinhole(s).

It should be noted that motion of one or more imaging detectors 102 maybe in directions other than strictly axially or radially, andoptionally, motions in several motion directions may be used. Therefore,the term “motion controller” may be used to indicate a collective namefor all motion controllers. It should be noted that the variouscontrollers may be combined, for example, the detector controller 136and pivot controller 138 may be combined to provide the differentmovements described herein.

Prior to acquiring an image of the subject 110 or a portion of thesubject 110, the imaging detectors 110, gantry 104, patient table 120and/or collimators 122 may be adjusted as discussed in more detailherein, such as to first or initial imaging positions, as well assubsequent imaging positions. The imaging detectors 102 may each bepositioned to image a portion of the subject 110. Alternatively, one ormore of the imaging detectors 102 may not be used to acquire data, suchas the imaging detectors 102 at ends of the detector arrays 106 and 108,which as illustrated in FIG. 1 are in a retracted position away from thesubject 110. Positioning may be accomplished manually by the operatorand/or automatically, which may include using other images acquiredbefore the current acquisition, such as by another imaging modality suchas CT, MRI, X-Ray, PET or ultrasound. Additionally, the detector units114 may be configured to acquire non-NM data, such as x-ray CT data.

After the imaging detectors 102, gantry 104, patient table 120, and/orcollimators 122 are positioned, one or more images are acquired by oneor more of the imaging detectors 102 being used. The image data acquiredby each imaging detector 102 may be combined and reconstructed into acomposite image, which may comprise two-dimensional (2D) images, athree-dimensional (3D) volume or a 3D volume over time (4D).

In one embodiment, the imaging detectors 102, gantry 104, patient table120, and/or collimators 122 remain stationary after being initiallypositioned. In another embodiment, an effective field of view for one ormore of the imaging detectors may be increased by movement such aspivoting one or more of the imaging detectors 102, rotating one or moreof the detector arrays 106 and/or 108 with the gantry 110, adjusting oneor more of the collimators 122, or moving the patient table 120.

In various embodiments, a data acquisition system (DAS) 160 receiveselectrical signal data produced by the imaging detectors 102 andconverts this data into digital signals for subsequent processing. Animage reconstruction device 162 and a data storage device 164 may beprovided in addition to the processing unit 150. It should be noted thatone or more functions related to one or more of data acquisition, motioncontrol, data processing and image reconstruction may be accomplishedthrough hardware, software and/or by shared processing resources, whichmay be located within or near the imaging system 100, or may be locatedremotely. Additionally, a user input device 166 may be provided toreceive user inputs (e.g., control commands), as well as a display 168for displaying images.

In operation, and as shown, for example, in FIG. 2, one embodimentincludes two detector arrays 106 and 108 (in opposed parallel alignment)that allow movement of a plurality of detector units 114, illustrated asdetector heads at the distal ends of a plurality of the detectorcarriers 116. In this embodiment, the two detector arrays 106 and 108are top and bottom detector arrays, respectively, wherein the subject110 is positioned therebetween on the patient table 120 with thedetector array 106 above the subject 110 and the detector array 108below the subject 110. As can be seen, the detector units 114 of thedetector arrays 106 or 108 are generally supported along a plane of thesupport member 112 and moveable relative thereto. For example, thesupport members 112 may be generally planar with each of the detectorunits 114 moveable with respect to the support member 112 such that thedetector units 114 move along parallel axes relative to the plane of thesupport member 112 (e.g., perpendicular to the plane of the supportmember 112 while maintaining a parallel relationship). In someembodiments, the support members 112 of the detector arrays 106 and 108are also arranged in an H-type configuration or parallel to each other.In one embodiment, the lower support member 112 is coupled to thepatient bed 120 (or other bed support) such that lower support member112 moves up and down with the patient bed 120. Alternatively, in someembodiments, the lower support member 112 is configured to move inunison with the up/down bed motion (e.g., moved simultaneously orconcurrently with the patient bed 120), but may not be coupled to thepatient bed 120.

In this embodiment, each of the detector units 114 of the detector array106 is individually and independently controllable to translate thedetector units 114 upwards and downwards with respect to the subject110. For example, one or more of the detector units 114 in the detectorarray 106 is operable to translate down until the detector unit 114 isproximate or adjacent the subject's body, while not contacting orcolliding with the subject 110. The distance of the detector units 114from the subject 110 may be controlled using one or more proximitysensors as known in the art. Thus, as shown in FIG. 2, a plurality ofthe detector units 114 of the detector array 106 is moved towards andpositioned proximate or adjacent the subject 110 (wherein some of thedetector units 112 are positioned at different distances from thesupport member 112 than other detector units 112).

It should be noted that optionally the support member 112 may be movedto facilitate positioning of the detector units 114. For example,depending on the size of the subject 110 and the maximum length of thedetector carriers 116, the support member 112 of the detector array 106may likewise move towards or away from the subject 110 (as illustratedby the T arrow), such that all of the detector units 114 are movedtogether to a position closer or farther from the subject 110 (e.g.,coarse movement) with the individual detector units 114 thereafter movedto position each in proximity or adjacent to the subject 110 (e.g., finetuning movement). The support members 112 also may provide otheroptional movement, such as later movement (left and right as viewed inFIG. 1) as illustrated by the L arrow. For example, depending on thesize or shape of the subject 110 and the positioning of the patienttable 120, the support member 112 may initially translate to align thedetector array 106 in a direction parallel to the coronal plane of thesubject 120.

The detector units 114 in the detector array 108 in the illustratedembodiment are in a fixed position relative to the patient bed 120. Forexample, the detector units 114 may be fixedly mounted to the gantry 104or to the support member 112 below the subject 110. In some embodiments,the detector carriers 116 are provided and may be fixed such thattranslating movement is not provided. In other embodiments, the detectorcarriers 116 are not provided with the detector units 114 fixedlymounted directly or through another fastening means (e.g., bracket) tothe gantry 104 or to the support member 112 below the subject 110.However, in other embodiments the detector units 114 below the subject110 may be movable with respect to the patient table 110. In variousembodiments, the detector units 114 below the subject 120 are stillindividually rotatable or tiltable, while in other embodiments nomovement is provided. Thus, the detector units 114 below the subject 110may be movable or non-movable.

It should be noted that the positioning of the plurality of detectorunits 114, in particular each of the individual detector units 114 inthe detector array 106 and/or 108 may be provided at the same time(e.g., concurrently or simultaneously) or at different times (e.g.,sequentially).

In operation, once positioned, one or more of the detector units 114 ofthe detector array 106 may rotate, for example, along the examinationaxis and/or transverse (e.g., perpendicular) to the examination axis toview the subject 110 from a plurality of different orientations. Themovement of the detector units 114 may be, for example, stepwise orcontinuous through a range of motion. The detector units 114 of thedetector array 108 likewise may rotate. The detector units 114 of thedetector arrays 106 and 108 may rotate at the same time (e.g.,concurrently or simultaneously) or may rotate at different times (e.g.,sequentially).

It should be noted that variations and modifications are contemplated.For example, as illustrated in FIG. 2, one of more edge detector units114 a and 114 b (two are illustrated, one at each end of the detectorarray 108) optionally may be located outside the edge of the patienttable 120 such that movement from below the patient table 120 to aposition above the patient table 120 (e.g., adjacent a side of thesubject 110) may be provided. The detector units 114 a and 114 b may bepositioned orthogonally with respect to the detector carrier 116 topoint sideways towards the subject 110. In one embodiment, the otherdetector units 114 of the detector array 108 are fixed, while in otherembodiments one or more of the other detector units 114 may beconfigured for movement as described herein.

Thus, in operation, the parallel movement of the detector units 114 inthe detector array 106 above the subject 110 and with respect to eachother allows positioning of the detector units 114 relative to any sizesubject 110. For example, each of the detector units 114 may beindividually translated downward to be positioned in proximity oradjacent to a portion of the patient 110. Additionally, because thedetector units 114 within the detector array 106 or 108 move along thesame parallel planes (e.g., upwards and downwards in respective lineardirections), the detector units 114 may be positioned with respect tosubjects 110 having different sizes and shapes, while maintaining thesame lateral gap (G) between each of the detector units 114. In variousembodiments, an increased number of detector units 114 then may be usedwhen imaging a larger subject 110.

For example, as shown in FIG. 3, the detector units 114 may beindividually moved to be positioned adjacent either a smaller subject182 or a larger subject 186 in the configurations 180 and 184,respectively. As can be seen, the same number of detector units 114 maybe used whether the subject 182 or 186 is smaller or larger.Additionally, as shown in FIG. 4, the edge detector units 114 a and 114b, as well as the edge detector unit 114 c in this embodiment (which isadjacent the edge detection unit 114 b) may be positioned on the side ofthe subject 182 and 186 at a height above the patient table 120.Additionally, as can be seen, one or more of the detector units 114 ofthe detector array 106 may extend downward along a side of the subject182 or 186 as well to be generally adjacent one or more of the edgedetector units 114 a, 114 b or 114 c to provide coverage around thesubject 182 or 186 (although some spacing may result due to the size orshape of the subject 120). It should be noted that in the illustratedembodiment, the other detector units 114 of the detector array 108located below the patient table 120 are coupled in a fixed position withrespect to the patient table 120, but may rotate as described in moredetail herein.

Different configurations also allow for imaging and coverage of smallerorgans. For example, as shown in FIG. 5, the detector units 114 may bepositioned proximate breasts 190 of the subject 110. As can be seen, thedetector units 114 of the detector array 106 may be positionedsurrounding at least a portion of the breasts 190. It should be notedthat not all of the detector units 114 are needed for imaging and assuch the detector units 114 i are inactive and do not collect dataduring imaging. Additionally, while the inactive detector units 114 iare shown in an extended position, the inactive detector units 114 i maybe in a non-extended or retracted position, for example, not moveddownward as illustrated in FIG. 5. The inactive detector units 114 i areshown extended merely to illustrate that other detector units 114provide the appropriate coverage. It also should be noted that othersmall organs or portions may similarly be imaged, such as arms, legs,knees, head, neck, small children and newborns, etc. As another example,a head 192 may be imaged as illustrated in FIG. 6, which may be anadult, child, or infant's head. As discussed in more detail herein, thedetector units 114 are moveable for positioning adjacent or proximatethe head 192. Again, one or more inactive detector units 114 i mayresult.

Additionally, as described herein the detector units 114 in the detectorarray 106 or 108 may be configured to move laterally (side to side). Forexample, as shown in FIG. 7, while the detector units 114 of thedetector array 108 under the patient table 120 are coupled thereto suchthat no movement upwards or downwards is provided, the detector units114 may move laterally (as indicated by the L arrow). For example, thesupport member 112 (shown in FIG. 1) of the detector array 108 may movethe detector units 114 laterally (movement of one of the detector nits114 is illustrated in phantom lines). In other embodiments, the detectorunits 114 may be configured for individual and independent lateralmovement. Accordingly, in operation, the detector units 114 are shiftedleft or right a distance to encompass the gap therebetween. Thus,additional coverage or new angles of view may be provided.

For example, the detector units 114 may move ½ the detector width insome embodiments, such that imaging in the two positions doubles thesampling. Similar lateral movement of the detector units 114 of thedetector array may be provided. It should be noted that the detectorunits 114 of the detector array 106 or the edge detector units 114 ofthe detector array 108 may be moved upwards or downwards in combinationwith the lateral movement so as to not contact the subject 110. Itshould be noted that SPECT reconstruction takes advantage of dataobtained from a plurality of viewing points relative to the subject 110.Thus, for example, lateral motion of the detector array increases theeffective number of such viewing points and thus may improve the qualityof the reconstructed image. For example, the acquisition time may bedivided into N (N may be chosen to be a small number such as 2, 3, ormore) segments. After the data has been acquired during an acquisitionsegment, at least one of the detector arrays may be laterally moved andthe next acquisition segment started or commenced. Optionally, in someembodiments, the lateral motion between acquisition segments is equal orapproximately 1/N of the lateral distance between adjacent imagingdetectors 102. During lateral motion the detector carriers may beactivated to prevent collision of the imaging detectors 102 with thesubject 110 or other structures, and/or to maintain close proximity tothe subject 110. Optionally, in some embodiments, the duration ofacquisition segments and the lateral motion between acquisition segmentsis not the same. Optionally, in some embodiments, the lateral motion isa continuous motion (e.g., slow continuous motion) and acquisitioncontinues throughout the lateral motion while associating the acquireddata with the location of acquisition (e.g., a record is keptassociating the acquired data with the location of the detectors 102).

As shown in FIG. 8, the support members 112 may support respectivedetector units 114, as well as an edge head support 200 on one or bothends of the support members 112. In the illustrated embodiment, the edgehead support 200 is positioned on opposite ends of the top and bottomsupport members 112. The edge head support 200 in the illustratedembodiment extends from the support members 112 (e.g., perpendicularthereto) with edge detector units 114 a and 114 b positioned on a sidethereof to face the subject 110. The edge head support 200 may beconfigured to move at least one of upwards and downwards (as illustratedby the T arrow) or laterally (as illustrated by the L arrow) withrespect to the respective support member 112. Thus, the edge detectorunits 114 a and 114 b may be provided with one or more additionalmovement axes relative to the other detector units 114, such as toaccommodate subjects 110 that are wider or larger. FIG. 9 illustratesthe edge head support 200 moved to position the edge detector units 114adjacent the subject 110. It should be noted that only one edge headsupport 200 may be provided or both of the edge head supports 200 may becoupled to one of the support members 112, for example, the supportmember 112 above or below the subject 110.

Other variations are contemplated. For example, the lower support member112 below the subject 110 may be configured for upward and downwardmovement (as illustrated by the T arrow). Optionally, lateral movementof the lower support member 112 may be provided. In this embodiment, thegantry 104 also may rotate the imaging detectors 102 about the subject110 as illustrated by the R arrow. Thus, as illustrated in FIG. 11, thedetector units 114 may be positioned in different radial positionsaround the subject 110, which may include translating movement of thedetector units 114 to avoid contact with the subject 110.

As other examples of variations, the support members 112 may be rotatedsuch that the detector units 114 now move laterally inward and outwardas shown in FIG. 12 instead of upwards and downwards. It should be notedthat in some embodiments, the support members 112 are in a fixedposition as shown in FIG. 12, which is 90 degrees offset from otherembodiments described herein. In this embodiment, the detector units 114similarly may be moved in proximity to the subject 110 (illustrated in aseated position) to perform, for example, a thyroid SPECT exam. Itshould be noted that in the various embodiments, one or more of thedifferent types of motion may be provided for the different componentparts. For example, in FIG. 12, the support members 112 may beconfigured to move as described in more detail herein.

A similar configuration to FIG. 12 is illustrated in FIG. 13. In thisembodiment, however, the subject 110 is standing. It should be notedthat the support members 112 in this embodiment may move upwards ordownwards. Additionally, in this embodiment, the detector units 114 ofthe detector array 108 are fixed (do not translate towards and away fromthe subject 110) and positioned adjacent a back of the subject 110.However, in other embodiments, as described in more detail herein, thedetector units 114 of the detector array 108 may be configured to move(e.g., translate towards and away from the subject 110).

In some embodiments, the amount of rotation that the detector units 114move may be different. For example, as illustrated in FIG. 14, the edgedetector 114 a may have limited (asymmetric) rotational movement rangerelative to other detector units 114, illustrated below the patienttable 120. Thus, for example, an angle α corresponding to rotationalmovement of one or more of the detector units 114 may be smaller thanthe angle θ corresponding to the rotational movement of one or more ofthe other detector units 114.

Other variations are contemplated. For example, as shown in FIG. 15, thedetector units 114 of the detector array 106 may be movable as describedherein and the detector units 114 of the detector array 108 may befixed. However, in this embodiment, a plurality of rollers 210, whichmay be fixedly coupled to a table support 212 allow movement of thepatient table 120 along a top of the table support 210. For example, thepatient table 120 rolls along the rollers 210 to position the subject110 at different axial positions along the examination axis (E). Itshould be noted that in this embodiment, the detector units 114 of thedetector array 106 are capable of tilting motion as shown.

As illustrated in FIG. 16, the detector units 114 may be located withinrespective housings 230 which may be a cover over the entire detectorunit 114. For example, the detector units 114 may be housed to protectthe subject 110 from (the relatively rapid) pivoting motion (illustratedby the arrow 232) of the detector unit 114. The housing 230 may have around cover (schematically depicted as the circular detector seen forexample in FIGS. 2-14). In some embodiments, the housing 230 includes acover 234 shaped with a section 235 of a cylinder that allows for thepivoting motion of the detector unit 114 around a pivoting point 236.When a flat collimator 237 is used, a gap 238 exists between the surface239 of the collimator 237 and the subject 110. This gap 238 causes areduction of the resolution and thus reduction of the image quality. Inone embodiment, a range of motion of the detector unit 114 is providedwithin the housing 230, such as rotational and/or translational movementas shown. Thus, in this embodiment, the coordinated pivoting and up/downmovement (lateral movement) of the detector units 114 is within thehousing 230, reduces or eliminates a dead space or gap 238 between thedetector and the subject 110.

Thus, various embodiments provide movable detector units that may beused for general purpose NM imaging, such as to define a general purposegamma camera with arrays of heads each having linear motion androtation.

Some embodiments provide a method 240 as shown in FIG. 17 for generalpurpose NM imaging. The method includes moving at 242 one or moresupport members having detector units coupled thereto as an array. Themovement positions the detector arrays with respect to a subject asdescribed herein. This initial movement may provide a coarse positioningof the detector units relative to the subject. Thereafter, one or moreof the detector units are moved at 244 as described herein toindividually and independently position the detector unit(s) withrespect to the subject. This movement may be a fine tuning movement insome embodiments to further position the detector units in closeproximity to the subject (e.g., within 1-5 cm, however other distancesmay be used). Once positioned, image data is acquired at 246, which mayinclude rotating the detector units as described herein. It should benoted that in some embodiments at least some of the imaging detectors102 (or detector units 114) move towards and away from the subject 110along substantially linear parallel directions. In some embodiments, atleast some of detector units 114 move towards and away from the subject110 along substantially linear opposing directions. The parallel motionreduces the likelihood of collision of two imaging detectors 102 ordetector units 114 without having to calculate respective locations andcontrol motion in a way that prevents such collision. Parallel motion ofthe imaging detectors 102 or detector unit 114 also provides that thelateral gaps (normal to the linear parallel motion) between two adjacentimaging detectors 102 or detector units 114 is fixed irrespective tomotion towards or away from the subject 110. In some embodiments, theimaging detectors 102 or detector units 114 may be closely packed, suchas in a closely packed “comb-like” array in order to obtain high systemsensitivity that increases with the number of imaging detectors 102 ordetector units 114 participating in the data acquisition. In contrast, aradially moving detector array is prone to detector collisions.Additionally, when imaging detectors 102 or detector units 114 move outradially large gaps between adjacent detectors may allow large portionsof the radiation to escape detection.

It should be noted that the various embodiments may be implemented inhardware, software or a combination thereof. The various embodimentsand/or components, for example, the modules, or components andcontrollers therein, also may be implemented as part of one or morecomputers or processors. The computer or processor may include acomputing device, an input device, a display unit and an interface, forexample, for accessing the Internet. The computer or processor mayinclude a microprocessor. The microprocessor may be connected to acommunication bus. The computer or processor may also include a memory.The memory may include Random Access Memory (RAM) and Read Only Memory(ROM). The computer or processor further may include a storage device,which may be a hard disk drive or a removable storage drive such as asolid-state drive, optical disk drive, and the like. The storage devicemay also be other similar means for loading computer programs or otherinstructions into the computer or processor.

As used herein, the term “computer” or “module” may include anyprocessor-based or microprocessor-based system including systems usingmicrocontrollers, reduced instruction set computers (RISC), ASICs, logiccircuits, and any other circuit or processor capable of executing thefunctions described herein. The above examples are exemplary only, andare thus not intended to limit in any way the definition and/or meaningof the term “computer”.

The computer or processor executes a set of instructions that are storedin one or more storage elements, in order to process input data. Thestorage elements may also store data or other information as desired orneeded. The storage element may be in the form of an information sourceor a physical memory element within a processing machine.

The set of instructions may include various commands that instruct thecomputer or processor as a processing machine to perform specificoperations such as the methods and processes of the various embodiments.The set of instructions may be in the form of a software program. Thesoftware may be in various forms such as system software or applicationsoftware and which may be embodied as a tangible and non-transitorycomputer readable medium. Further, the software may be in the form of acollection of separate programs or modules, a program module within alarger program or a portion of a program module. The software also mayinclude modular programming in the form of object-oriented programming.The processing of input data by the processing machine may be inresponse to operator commands, or in response to results of previousprocessing, or in response to a request made by another processingmachine.

As used herein, the terms “software” and “firmware” are interchangeable,and include any computer program stored in memory for execution by acomputer, including RAM memory, ROM memory, EPROM memory, EEPROM memory,and non-volatile RAM (NVRAM) memory. The above memory types areexemplary only, and are thus not limiting as to the types of memoryusable for storage of a computer program.

Also, as used herein, the terms “system,” “unit,” or “module” mayinclude a hardware and/or software system that operates to perform oneor more functions. For example, a module, unit, or system may include acomputer processor, controller, or other logic-based device thatperforms operations based on instructions stored on a tangible andnon-transitory computer readable storage medium, such as a computermemory. Alternatively, a module, unit, or system may include ahard-wired device that performs operations based on hard-wired logic ofthe device. The modules or units shown in the attached figures mayrepresent the hardware that operates based on software or hardwiredinstructions, the software that directs hardware to perform theoperations, or a combination thereof. As used herein, an element or steprecited in the singular and proceeded with the word “a” or “an” shouldbe understood as not excluding plural of said elements or steps, unlesssuch exclusion is explicitly stated. Furthermore, references to “oneembodiment” are not intended to be interpreted as excluding theexistence of additional embodiments that also incorporate the recitedfeatures. Moreover, unless explicitly stated to the contrary,embodiments “comprising” or “having” an element or a plurality ofelements having a particular property may include additional suchelements not having that property.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the variousembodiments without departing from their scope. While the dimensions andtypes of materials described herein are intended to define theparameters of the various embodiments, they are by no means limiting andare merely exemplary. Many other embodiments will be apparent to thoseof skill in the art upon reviewing the above description. The scope ofthe various embodiments should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled. In the appended claims, the terms“including” and “in which” are used as the plain-English equivalents ofthe respective terms “comprising” and “wherein.” Moreover, in thefollowing claims, the terms “first,” “second,” and “third,” etc. areused merely as labels, and are not intended to impose numericalrequirements on their objects. Further, the limitations of the followingclaims are not written in means-plus-function format and are notintended to be interpreted based on 35 U.S.C. § 112, sixth paragraph,unless and until such claim limitations expressly use the phrase “meansfor” followed by a statement of function void of further structure.

This written description uses examples to disclose the variousembodiments, including the best mode, and also to enable any personskilled in the art to practice the various embodiments, including makingand using any devices or systems and performing any incorporatedmethods. The patentable scope of the various embodiments is defined bythe claims, and may include other examples that occur to those skilledin the art. Such other examples are intended to be within the scope ofthe claims if the examples have structural elements that do not differfrom the literal language of the claims, or the examples includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

What is claimed is:
 1. An imaging system comprising: at least fivedetector carriers, wherein each of the at least five detector carrierscomprises a corresponding detector head positioned at a distal end thatincludes a solid state gamma detector and is configured to pivot;wherein the at least five detector carriers are configured to positionthe corresponding detector heads during imaging of an object using atleast some of the detector heads, wherein at least one detector head ofthe at least five detector carriers is configured to not be used forimaging and in a retracted position away from the object.
 2. The imagingsystem of claim 1, wherein at least one of the detector heads isconfigured to be interposed between the at least one head not used forimaging and the object being imaged.
 3. The imaging system of claim 1,wherein at least two of the detector heads are configured to beselectively not used for imaging and in a retracted position away fromthe object during imaging of the object.
 4. The imaging system of claim1 further comprising a patient table configured to support the objectbeing imaged, wherein the patient table defines a lateral directionalong the patient table and a vertical direction perpendicular to thepatient table, wherein each of the detector heads is configured to bepositioned at a corresponding vertical distance from the patient tabledefined along the vertical direction, wherein the magnitudes of thevertical distances define a curve plotted along the lateral direction,wherein the curve has an inflection point.
 5. The imaging system ofclaim 4, wherein the curve has multiple inflection points.
 6. Theimaging system of claim 5, wherein the curve defines a first portionthat is convex with respect to the patient table.
 7. The imaging systemof claim 6, wherein the curve defines a second portion that is adjacentthe first portion, wherein the second portion is concave with respect tothe patient table.
 8. The imaging system of claim 7, wherein the curvedefines a third portion that is adjacent the first portion on a sideopposite the second portion, wherein the third portion is concave withrespect to the patient table, wherein at least one detector headcorresponding to the first portion is configured to be at leastpartially interposed along the lateral direction between two portions ofthe object being imaged.
 9. A method for positioning detector heads fora system comprising at least five detector carriers, wherein each of theat least five detector carriers comprises a corresponding detector headpositioned at a distal end of the corresponding carrier and including asolid state gamma detector, each detector head configured to pivot, themethod comprising: positioning, during imaging of an object, at leastsome of the detector heads in an active position proximal to the objectbeing imaged for imaging the object; and positioning, during imaging ofthe object, at least one detector head that is not used for imaging ofthe at least five detectors in a retracted position away from theobject.
 10. The method of claim 9, further comprising positioning atleast one of the detector heads in the active position at a locationinterposed between the at least one detector head that is not used forimaging and the object being imaged.
 11. The method of claim 9, whereinthe system comprises a patient table configured to support the objectbeing imaged, wherein the patient table defines a lateral directionalong the patient table and a vertical direction perpendicular to thepatient table, the method further comprising: positioning each of thedetector heads at a corresponding vertical distance from the patienttable defined along the vertical direction, wherein the magnitudes ofthe vertical distances define a curve plotted along the lateraldirection, wherein the curve has an inflection point.
 12. The method ofclaim 11, wherein the curve has multiple inflection points.
 13. Themethod of claim 12, wherein the curve defines a first portion that isconvex with respect to the patient table.
 14. The method of claim 13,wherein the curve defines a second portion that is adjacent the firstportion, wherein the second portion is concave with respect to thepatient table.
 15. The method of claim 14, further comprisingpositioning at least one detector head corresponding to the firstportion at a position at least partially interposed along the lateraldirection between two portions of the object being imaged, wherein thecurve defines a third portion that is adjacent the first portion on aside opposite the second portion, wherein the third portion is concavewith respect to the patient table.
 16. An imaging system comprising: atleast five detector carriers, wherein each of the at least five detectorcarriers comprises a corresponding detector head positioned at a distalend that includes a solid state gamma detector and is configured topivot; and a patient table configured to support an object being imaged,wherein the patient table defines a lateral direction along the patienttable and a vertical direction perpendicular to the patient table;wherein each of the detector heads is configured to be positioned at acorresponding vertical distance from the patient table defined along thevertical direction, wherein at least one of the detector heads isconfigured to extend along the vertical direction to be interposedbetween portions of anatomy imaged along the lateral direction, whereinthe magnitudes of the vertical distances define a curve plotted alongthe lateral direction, wherein the curve has an inflection point. 17.The imaging system of claim 16, wherein the curve has multipleinflection points.
 18. The imaging system of claim 17, wherein the curvedefines a first portion that is convex with respect to the patienttable.
 19. The imaging system of claim 18, wherein the curve defines asecond portion that is adjacent the first portion, wherein the secondportion is concave with respect to the patient table.
 20. The imagingsystem of claim 19, wherein the curve defines a third portion that isadjacent the first portion on a side opposite the second portion,wherein the third portion is concave with respect to the patient table,wherein at least one detector head corresponding to the first portion isconfigured to be at least partially interposed along the lateraldirection between two portions of the object being imaged.